Polyolefin Composition for 3D Printing Dimensional Stability
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Solution Overview
Problem
Conventional additive manufacturing technologies face challenges with polyolefins due to residual stress, shrinkage, warpage, and curling issues, particularly with semi-crystalline polymers, which affect the consistency between the virtual project and the final printed part.
Innovation Solution
A compounded polymer composition comprising a heterophasic copolymer with a polyolefin matrix phase and a dispersed phase, combined with a nucleating agent and filler, which achieves reduced physical distortion, isotropic shrinkage, and lower coefficient of linear thermal expansion, utilizing a synergistic combination of low crystalline ethylene/α-olefin copolymer, nucleating agent, and filler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If semi-crystalline polymers are used in additive manufacturing, then mechanical strength and fatigue resistance are improved, but residual stress, shrinkage, warpage, and curling issues worsen
Solution Approach 1:
The patent modifies the crystalline structure parameters of the polymer by controlling crystal size, distribution, and orientation through processing conditions. This allows the material to maintain high mechanical strength while reducing the excessive crystallinity that causes shrinkage and warpage. The crystallinity is optimized to a specific range that balances mechanical properties with dimensional stability.
Solution Approach 2:
The invention creates a composite structure within the polymer material by combining crystalline and amorphous phases in specific proportions and arrangements. This internal composite structure allows the material to exhibit both the strength of crystalline regions and the dimensional stability of controlled crystallization, effectively resolving the contradiction between mechanical strength and manufacturing precision.
2Strength
If high crystalline polymers are used, then mechanical properties are improved, but shrinkage and warpage increase
Solution Approach 1:
The patent applies local quality by creating regions of different crystallinity within the polymer structure. High-crystallinity regions provide mechanical strength, while low-crystallinity or amorphous regions accommodate dimensional changes and reduce overall shrinkage. This spatial variation in crystalline quality allows simultaneous achievement of mechanical properties and shape stability.
Solution Approach 2:
The invention changes the crystallization parameters by controlling cooling rates, nucleation density, and crystal growth conditions to achieve an optimal crystallinity level that provides sufficient mechanical strength without excessive shrinkage and warpage.
3Ease of manufacture
If conventional polymers are used in additive manufacturing, then ease of manufacture is maintained, but consistency between virtual project and final printed part deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-controlling the crystalline structure and properties of the polymer material before the additive manufacturing process. The polymer is pre-formed with specific crystallinity, molecular weight distribution, and thermal properties that ensure consistent dimensional stability during printing, thereby maintaining ease of manufacture while improving consistency between the digital model and final part.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compounded polymer composition exhibits reduced unidirectional shrinkage, isotropic shrinkage, and lower warpage, maintaining dimensional stability and consistency in additive manufacturing processes, while providing improved mechanical properties such as strength and fatigue resistance.
Implementation Method 1
solidifying the melt to form a printing layer
Implementation Method 2
a nucleating agent
Data Source
AI summary
A compounded polymer composition suitable for manufacturing of isotropic three-dimensional printed articles may include an impact copolymer, a low crystalline ethylene/α-olefin copolymer; a nucleating agent; and filler, where the impact copolymer may include a matrix phase comprising a propylene-based polymer or copolymer; and a dispersed phase in the matrix phase, the dispersed phase comprising an ethylene-based copolymer, the ethylene-based copolymer having a C3-C12 comonomer, wherein the dispersed phase has a different composition than the matrix phase.